Two-dimensional (2D) materials have attracted enormous attention due to their functional applications in energy storage. In this work, a low-temperature molten-salt chemical exfoliation methodology is developed for producing free-standing 2D mesoporous Si through deintercalation of CaSi2 in excess molten AlCl3 at 195 °C. The average dimension of these sheets is 1.5 μm, and the thickness of a single sheet is approximately 10 nm. The as-prepared 2D Si has a Brunauer–Emmett–Teller surface area of 154 m2·g?1 and an average pore size of 5.87 nm. With this unique structure, the 2D Si exhibits superior Li-storage performance, including a reversible capacity of 2,974 mA·h·g?1 at 0.2 C, reversible capacities of 2,162, 1,947, and 1,527 mA·h·g?1 at 0.8, 2, and 5 C after 200 cycles, and a capacity retention of 357 mA·h·g?1 even at 30 C (90 A·g?1).
Atomic composition tuning and defect engineering are effective strategies toenhance the catalytic performance of multicomponent catalysts by improvingthe synergetic effect; however, it remains challenging to dramatically tune the active sites on multicomponent materials through simultaneous defect engineeringat the atomic scale because of the similarities of the local environment. Herein,using the oxygen evolution reaction (OER) as a probe reaction, we deliberatelyintroduced base-soluble Zn(II) or Al(III) sites into NiFe layered double hydroxides(LDHs), which are one of the best OER catalysts. Then, the Zn(II) or Al(III) siteswere selectively etched to create atomic M(II)/M(III) defects, which dramaticallyenhanced the OER activity. At a current density of 20 mA·cm?2, only 200 mV overpotential was required to generate M(II) defect-rich NiFe LDHs, which is the best NiFe-based OER catalyst reported to date. Density functional theory(DFT) calculations revealed that the creation of dangling Ni–Fe sites (i.e., unsaturated coordinated Ni–Fe sites) by defect engineering of a Ni–O–Fe site at the atomic scale efficiently lowers the Gibbs free energy of the oxygen evolutionprocess. This defect engineering strategy provides new insights into catalysts atthe atomic scale and should be beneficial for the design of a variety of catalysts.
Nano Research - The first author, Fanbin Meng, and the second author, Ying Wang, contributed equally to this work was unfortunately forgotten to write on the first pages of the main text and the... 相似文献
Nano Research - A spin-coating method was applied to obtain thinner and smoother PEO/LiClO4 polymer electrolyte films (EFs) with a lower level of crystallization than those obtained using a... 相似文献
Nano Research - Developing multifunctional nanoparticles to support new therapy models is a promising and challenging task to address the current dilemma on antitumor treatment. Herein, we... 相似文献
A two-step approach was reported to fabricate cobaltous hydroxide/γ- nickel oxide hydroxide/reduced graphene oxide (Co(OH)2/γ-NiOOH/RGO) nanocomposites on nickel foam by combining the reduction of graphene oxide with the help of reflux condensation and the subsequent hydrothermal of Co(OH)2 on RGO. The microstructural, surface morphology and electrochemical properties of the Co(OH)2/γ-NiOOH/RGO nanocomposite were investigated. The results showed that the surface of the first-step fabricated γ-NiOOH/RGO nanocomposites was uniformly coated by Co(OH)2 nanoflakes with lateral size of tens of nm and thickness of several nm. Co(OH)2/γ-NiOOH/RGO nanocomposite demonstrated a high specific capacitance (745 mF/cm2 at 0.5 mA/cm2) and a cycling stability of 69.8% after 1000 cycles at 30 mV/cm2. γ-NiOOH/RGO//Co(OH)2/γ-NiOOH/RGO asymmetric supercapacitor was assembled, and maximum gravimetric energy density of 57.3 W?h/kg and power density of 66.1 kW/kg were achieved. The synergistic effect between the highly conductive graphene and the nanoflake Co(OH)2 structure was responsible for the high electrochemical performance of the hybrid electrode. It is expected that this research could offer a simple method to prepare graphene-based electrode materials. 相似文献
The dynamic behavior of octahedral gold nanoparticles (NPs) and nanoparticle clusters (NPCs) in aqueous solution is studied by in-situ liquid-cell transmission electron microscopy (TEM). The octahedral Au NPs/NPCs show preferential orientations in the liquid cell, due to the interaction with the SiNx window. The Au NPs show long-range reversible hopping and three-dimensional (3D) rotational motions in the liquid environment. At the same time, the Au NPCs and NPs perform slow stick-slip and stick-roll motions, respectively, with a centripetal trend. The centripetal motions were explained by a liquid evaporation-induced radial flow model, in which the NPCs/NPs trajectories are controlled by Stokes forces and surface friction by the silicon nitride window. The calculated radius-dependent force (Fc) on the NPCs/NPs shows a semi-linear correlation with the distance r between the NPCs/NPs and the center of mass, accompanied with stochastic fluctuations, in agreement with the model predictions. This work thus demonstrates the effectiveness of in situ liquid-cell TEM for the in-depth understanding of complicated liquid flow and force interactions in nanomaterials.
